The boxes below show the results of a Monte Carlo simulation run against polling data for each of the contested states in the 2012 election. Dark lines are simulations where the outcome was a Romney win, so the darker the box, the better the odds for Romney and the reverse -- lighter the box -- for President Obama. For example, North Carolina is particularly dark because of Romney's lead there. Each box represents 1600 simulated elections. (N.B. this is in black and white because red and blue get nuclear when plotted close to one another. Data from Huffpo's pollster api.)
— Jeff Larson, @thejefflarson